'04 Ford F150 brake light issue


#1

A friend of mine has a 2004 F150. The tail lights and the 3rd brake light are working but the rear brake lights, flasher and turn signals have stopped working. Any idea as to what could be wrong? I googled the problem and did find one person with the same issue in a 2001 F150. There apparently was a recall (#05S28) of the SCDS (Speed Control Deativation Switch) but that vehicle kept blowing fuse 13. My friend checked his fuses and they were all ok,


#2

I’d think the multi function ( turn signal etc ) switch…or, very commonly, the plug on the back of it.
Sometimes the little ears that hold the wire pigtails inside the gang plug will break from old age allowing a wire or two to come loose and loose connection.


#3

The brake light, turn signal, and flashers use the same bright filament, and the tail lights use a dimmer filament. Are you sure the bulbs are not blown on the bright filament? It would be unusual for both to go at the same time, but not impossible.


#4

Which body style 2004 F150 . . . ?

New body style?

Heritage body style?

Round looking?

Square looking?


#5

Heritage body style.


#6

Try changing the bulbs first. Post back with the results.


#7

If you have a DVM you could remove one of the bulbs and test the filament resistance. They probably have two filaments, and both should be just a few ohms. If the bulb is ok, then use the DVM to probe the voltages at the pins. Since it is happening on both sides, it has to be something in common with both sides, maybe a broken ground wire.


#8

Since the third brake light is working this means power is getting past the brake switch. There is a splice in the wire connection after the switch and before the multi-function switch. Verify power from brake switch is getting to pin 9 (Lt grn wire) of the multi-function switch. If it is then the M-F switch is suspect. If no power is getting to the pin then suspect a bad connection at splice S231.


#9

Considering how this is wired & what is and isn’t working I think Ken Green nailed it +1 for checking the multi function switch & it’s wiring.

If this has adjustable tilt, try raising the wheel & see if that makes a difference.


#10

Try replacing the bulbs first. After that the turn signal switch would be the next thing I’d check.


#11


#12

Turns out it was just the bulbs themselves…


#13

Thanks for posting back the results. Stranger things can happen.


#14

I too thank you for posting back. Too often we never hear.
Happy motoring.


#15

I found on mine when tilted all the way down, a turn signal would not work, try changing the tilt of the steering wheel.